15MW風機之半潛式浮台之運動性能分析

Abstract

本研究建立以IEA 15MW風機為參考對象，製作一1/100的半潛式VolturnUS-S浮台模型來進行有無波浪的條件下的起伏、俯仰與橫搖三自由度運動量測。進行自由衰減實驗，求得阻尼係數與自然頻率；進行耐海性能實驗，在不同頻率規則波中運動求得反應振幅運算子。 起伏自然衰減實驗顯示初始位移量越大，阻尼比越高，與IEA所模擬趨勢相同，自然頻率與IEA的縮尺頻率相同。 俯仰與橫搖自然衰減實驗顯示初始角度越大，阻尼比越高，與IEA所模擬趨勢相同，但高於IEA模擬的阻尼比，此乃因模型雷諾數低造成黏性效應高所致。 俯仰與橫搖自然衰減實驗不同初始角度得到之自然頻率高於IEA模擬的自然頻率，有所誤差是因模型無風機導致轉動慣量偏低所致。 耐海性能實驗結果顯示起伏、俯仰之共振頻率與自然衰減實驗所求得之自然頻率相符。

This study established a 1/100 scale semi-submersible VolturnUS-S platform model based on the IEA 15MW reference wind turbine to measure the heave, pitch and roll three degrees of freedom under conditions of having or not having waves. The damping coefficients and natural frequencies were obtained by conducting free decay test. The response amplitude operators were obtained by conducting the seakeeping test with different frequency regular waves. The results of the free decay experiments for heave showed that the higher the initial displacement, the higher the damping ratio, which is consistent with the results simulated by IEA. The natural frequency is the same as that of the scaled IEA calculated natural frequency. The results of the free decay experiments for pitch and roll showed that the higher the initial angles, the higher the damping ratios, which are consistent with the trend simulated by IEA. However, the damping ratios are higher than those of the IEA simulated results. It may due to the low Reynolds number of the model and result in high viscous effects. The natural frequencies of pitch and roll obtained from the free decay experiments were higher than those of the IEA simulation. It may due to the low moment of inertia of the model without the wind turbine. The resonance frequency of heave and pitch obtained from the seakeeping test are consistent with the free decay experiments results.